Calibration of High-Dose LIF Crystal Optical Dosimeters

Calibration of HIGH-DOSE LiF Crystal OPTICAL Dosimeters.  n. gee and R. Brey (Idaho State University, Health Physics Program, Campus Box 8106, Pocatello, ID 83209)

Lithium fluoride is commonly used in thermoluminescent dosimeters (TLDs) because it is linear over the range of absorbed dose required for most health physics applications. However, LiF crystals can be used for very high-absorbed doses in the range of 10² to 10⁷ Gy.  The measured quantity related to dose in these high-dose applications is optical absorption rather than light intensity produced during thermoluminescence.  As with any dosimeter that is not based on the direct measurement of energy absorption, high-dose lithium fluoride crystals require specific calibration prior to use.  We calibrate these dosimeters based upon the dose measured using a graphite calorimeter and delivered using an electron accelerator.  The net optical density measured using a spectrophotometer is correlated to the absorbed dose.   

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